Photographic emulsions containing trinuclear cyanine dyes



Dec. 26, 1950 T. R. THoMPsoN 2,535,995

PHOTOGRAPHC EMULSIONS CONTAINING TRINUCLEAR CYANINE DYES Filed April 30,1949 Fig. I.

Fig. 2.

Fig. 5. N

INVENTOR Thomas R. Thompson Patented Dec. 26, 1,950

PHOTOGRAPHIC EMULSIONS CONTAINING TRINUCLEAR CYANINE DYES Thomas R.Thompson, Binghamton, N. Y., as-

signor to General Anilne & Film Corporation, New York, N. Y., acorporation of Delaware Appucation April 30,1949, serial No. 90,711

4 Claims.

This invention relates to photographic gelatine silver-halide emulsions,and more particularly, to photographic emulsions sensitized by means ofnew trinuclear cyanine dyes containing a terminal -membered nitrogenousheterocyclic ring system.

The use of sensitizing dyes, particularly in multilayer color lm, posesmany problems. It is known that sensitizing dyes operate by dyeing thesilver-halide grain. To do this, they must be adsorbed to thesilver-halide. I f they are displaced from the silver-halide grains,they lose their eiiectiveness as sensitizers. It is also known that manycolor ormers used in color photography have greater affinity forsilver-halides than the sensitizers, and act to displace the same fromthe silver-halide grains. One must, therefore, select a sensitizer whichwill not be so displaced.

Another problem arises as regards the migration of the sensitizers fromone emulsion to another. Where this ensues, color distortion is theinevitable result. Many proposals have been made dealing with theanchoring of compounds in silver-halide emulsions, the most noteworthybeing the use of a long alkyl chain (see Wilmanns et al., United StatesPatent 2,186,849)

It is, therefore, necessary when providing sensitizers particularly forcolor photography, to make certain that they have (1) the propersensitizing power, (2) the ability to withstand displacement iromsilver-halide grains by color formers, and (3) the ability to resistdiiusion from one sensitized emulsion to another.

Elorts which satisfy the last prerequisite, unfortunately, often lead tocompounds which will not meet the rst two tests. Thus, it is known thatthe sensitizing power of cyanine dyes varies with the substituent on thecyanine` N-atoms. Where this substituent is alkyl, the power decreasesas the chain length increases. Hence, if a long alkyl chain be used toanchor the dye in the emulsion, we end up with a product of little or nosensitizing power. The use of other expedients to anchor the dye, on theother hand, often gives products incapable of withstanding thedisplacement action of color formers insofar as the silver-halide grainsare concerned. It is thus manifest that the provision of sensitizershaving the necessary prerequisite is a difficult problem, to say theleast.

It is known that many cyanine dyes sensitize photographic silver-halideemulsions to high red sensitivity. Most of these dyes, however, are notsuitable for sensitizing silver-halide emulsions containing colorcoupling components. This is thought to be due to a physicaldisplacement which the sensitzing dye undergoes when color couplingcomponents are added. That is, the sensitizer is` adsorbed to thesurface of the silver-halide grain, and then, with addition of colorcoupling component, is displaced therefrom. Moreover, most of thecyanine dyes are incompatible with silver-halide emulsion Stabi* lizers,such as, for example, mercapto-substituted tetrazoles.

An object of the present invention is to provide photographicsilver-halide emulsions with trinuclear sensitizing dyestuffs containinga. terminal -membered nitrogenous heterocyclic ring system.

A further object is to provide such dyes which are free from thedisadvantages noted above.

Other objects and advantages of this invention will become apparent byreference to the following specication in which its preferred detailsand embodiments are described,

This invention is based on the discovery that trinuclear cyanine dyescontaining a terminal -membered ring system not only sensitize aphotographic silver-halide emulsion to high red sensitivity, but arealso compatible with color coupling components for the cyan dye imageand with practically all emulsion stabilizers including themercapto-substituted tetrazoles. In the latter combination thesensitizing action of the dyes is not impaired nor diminished. Inaddition to these desirable characteristics, it has been further foundthat when the dyes are used in conjunction with color couplingcomponents for the blue-green image, the spectral curves of these dyesshow a desirable gap in the green region oi the spectrum, i. e., the dyesensitivity is more selective to the red spectral region. Thesensitizing capacity of these dyes is not only maintained in thepresence of color coupling components for the blue-green image,especially those components containing long alkyl chains, but is in partrendered more selective.

Some of the trinuclear cyanine dyes of this invention, which sensitizeemulsions to the regions of longer wavelengths, are of extreme value inthe manufacture of infrared silver-halide emulsions which can be exposedthrough light yellow lters instead of the ordinarily used heavy grayfilters in view of their low sensitizing power for the green, yellow andred. An additional advantage of these dyes is their ability to remainfixed in the layer in which they are originally deposited.

The trinuclear cyanine dyes fullling the above advantage are obtained inexcellent yield and in readily puriiiable form by treating a S-alkyl,S-aryl, or 3-aralkyl substituted -membered ketomethylene heterocycl ccompound containing a reactive methylene group adjacent to a keto groupoi the type commonly employed in merocyanine dyes with a thiazolonecyanine dye salt A wherein R represents hydrogen or an alkyl group, e.g., methyl, ethyl, propyl or butyl, R being only alkyl when m represents1, R1 and R2 which may be alike or different represent an alkyl, allyl,aryl, or aralkyl group, e. g., methyl, ethyl, propyl, phenyl, naphthyl,tolyl, benzyl, phenethyl and the like, R3 represents an aliphatic, aryl,aralkyl or substltuted group of this type, e. g., methyl, ethyl, propyl,butyl, hydroxyethyl, ethcxyethyl, phenyl, tolyl, naphthyl, benzyl,phenethyl, menaphthyl and the like, m represents a positive integer offrom l to 3, X represents an acid radical, e. g., chloride, bromide,iodide, or alkyl sulfate, alkyl p-toluenesulfonate or perchlorate, Yrepresents the residue of a -membered heterocyclic nitrogenous ringsystem of the type used in merocyanine dyes, e. g., N-alkyl, N -allyl,N-aryl, N`aralkyl substituted derivatives of rhodanic acid,-pyrazolones, thiazolediones, thiazolones, oxazolediones,thiohydantoins, and the like, and Z represents the residue of aheterocyclic nitrogenous nucleus of the type used in cyanine dyes, e.g., oxazoles, thiazoles, selenazoles, and their polycyclic homologues,such as those of the benzene, naphthalene, acenaphthene, and anthraceneseries, pyridine, and its polycyclc homologues, such as quinoline andaand ,B-naphthaquinolines, perinaphthiazoles, indolenines, diazines,such as pyrmidines, and quinazolines, diazoles (e. g., thio-diazoleoxazolines, pyrrolines, thiazolines and selenazolines (the polycycliccompounds of these series being substituted if des'red in thecarbocy-clic rings with one or more conventional groups, such as alkylor aryl, as below, amino, hydroxy, alkoxy, i. e., methoxy, ethoxy, etc.,and methylene dioxy groups, or by halogen atoms, i. e., chlorinebromine, etc.)

The N-substituted 5-membered ketomethylene heterocyclic compounds of thetype commonly employed in merocyanine dye synthes's, which are treatedwith a thiazolone cyanine dye intermediate are characterized by thefollowing gcneral formula:

wherein Y and R1 have the same values as above.

As typical examples of such compounds, the following may be mentioned:

3ethylrhodanine 3-al1ylrhodanlne 3-phenylrhodanine S-benzylrhodaninezole 3-phenyl-4keto2-seleno-tetrahydro-s'elenazole3-propyl-4-keto-2-seleno tetrahydro thiazolel-phenyl-S-methyl--pyrazolone l-methyl-5-pyrazolone1,3-dimethy1-5-pyrazolone 1,3-diphenyl--pyrazolonc3-phenyl-2,4-thiazoledione 2-diphenylamino-3-ethyl-4 (5) -thiazolone3-ethyl-2-thio2,4(3,5) -oxazoledione 3-ethyl-1-phenyl-Z-thiohydantoin,and the like.

The thiazolone cyanine dye intermediates utilized as the coreactantswith the foregoing N- suostituted 5-membered ketomethylene heterocycliccompounds, are characterized by the following general formulae:

wherein R2, R3, X and Z have the same values as above, R4 represents anaryl group of the benzene and naphthalene series such as phenyl,chlorophenyl, diphenyl or naphthyl, R.; represents either hydrogen or anacetyl group, Re Iepresents an alkyl or aralkyl group, e. g., methyl,

ethyl, propyl, isopropyl, benzyl, -phenethyl, and the like, R7represents an alkyl group, e. g., methyl, ethyl, propyl, isopropyl,butyl, isobutyl, etc., and 1L represents a positive integer of from 1 to3, and W represents the atoms necessary to complete a saturatednitrogenous heterocyclic nucleus, such as, for example, piperidine, andy-pipecoline, pyrrolidine, morpholine, tetrahydroquinoline, and thelike.

The dyestufl intermediates illustrated by the Formulae a and c areprepared according to the method described in my copending applicationSerial No. 65,571, led on December 21, 1948, and the intermediatesillustrated by the second Formula b are prepared according to the methoddescribed in my copending application Serial No. 66,572, filed onDecember 21, 1948.

The dyestui intermediates illustrated by Formula a are, in general,obtained by treating a diarylformamdine or its vinylog such as,Ll--ani-V linoacrolein anil hydrochloride or glutaconic aldehyde dianilhydrochloride, in the presence of an acid condensing agent, such asacetic anhydride or in the presence of a basic condensing agent, such astriethylamine or piperidine)` with a thiazolone cyanine dye.

The dyestuf intermediates illustrated by `For-- mula b are obtained bytreating a triazolone cyanine dye with an aliphatic acid anhydride 1nthe presence of a mixture of pyridine and triethylamine followed bytreatment with phosphorous pentasulde to yield the thioketone derivativewhich is subsequently alkylated with an alkylating agent in the usualway to yield the thioether derivative.

AThe dyestul intermediates containing a terminal saturated heterocyclicnitrogenous ring nucleus are prepared by treating a thiazolone cyaninedye with a diarylforinamidine or its Vinylog in the presence or absenceof an aliphatic alcohol as a diluent and in the presence of a saturatedheterocyclic nitrogenous compound, such as morpholine, piperidne,tetrahydroquinoline, and the like. i

The thiazolone cyanine dyes utilized in preparing the foregoingintermediates are characterized by the following general formula:

wherein R2, R3, X and Z have the same values as above, and are preparedaccording to the method described in my copending application Serial No.786,814, filed November 18, 1947. In general, the method consists ofcondensing a substituted thioamide with an a-halogen acetic acid. Thecompounds, in view of their ketomethylene conguration undergo keto-enoltautomerism, i. e., the keto group enolizes to form a hydroxyl group.

The following examples describe the preparation of some of thethiazolone cyanine dye intermediates illustrated by Formulae a and bwhich are utilized in the preparation` of the trinuclear cyanine dyes.

Example I @aired-"i and cc. of acetic anhydride was heated at 140 C. for30 minutes. After cooling, the prod-M uct was precipitated with ether`and purified by` dissolving in a small amount of methanol iollowed byprecipitation with ether. A yield of 5.9 grams of yellow green crystals,having a melting` point at 21S-215 C., was obtained.

was heated at 120 C. for 30 minutes. Fifteen grams of phosphoruspentasulde were added in portions and the reaction mixture stirred at120 C. for 30 minutes. The product was isolated by pouring the reactionmixture into 300 cc. of water. The product was puried by washing withWater and subsequently grinding with acetone. A yield of 10.9 grams ofyellow glistening crystals melting at Z55-260 C. was obtained. Theproduct was fused with l0 cc. of methyl sulfate at C. for 10 minutes toyield a thick solution which upon treatment with an acetone solution ofsodium iodide deposits yellow crystals.

Example III A mixture of 75 cc. of pyridine, 10 cc. of propicnicanhydride, 10 co. of triethylamine, and 13 grams of the thiazolonecyanine dye of the following structure:

0= eine N da was heated with stirring at C, for 20 minutes. During thecourse of 10 minutes, a total of 10 grams of phosphorus pentasulde wasadded in portions at 120 C. After an additional 10 minutes heating andstirring at 120 C., the mixture was poured into cold water and stirreduntil the first formed oil solidified. The crude precipitated as theiodide, by adding 25 cc. of methanol containing 20% sodium iodide. Theproduct was washed with water and puried by boiling out withisopro-panol. A yield of 4.3 grams of a product melting at 225-228" C.was obtained.

Example IV 02H5 CH3 CHT S C=C S one-o CH3 .ha goed N hlt CHZsoi Amixture of 15 cc. of pyridine, 2 cc. of propionic anhydride, 2 cc. oftriethylamine, and 2.0 grams of the thiazolone cyanine dye of thefollowing structure:

was heated at 120 C. for 3 minutes. There were then added 2 grams ofphosphorus pentasulde and the mixture heated at 115 C. for 15 minutes.

A dark red oil was precipitated by the addition of 100 ec. of water andwashed with Water by decantation. The product was fused with 3 cc. ofmethyl sulfate at 95 C. for l0 minutes to yield 4.5 grams of ayellow-orange solution which 'A mixture of 0.5 gram of the product ofEX- ample III, 0.3 gram of fanilinoacrolein anil hydrochloride, 10 cc.of methanol, and 0.5 gram of piperidine was heated at reiiux for`5minutes.- The reaction mixture was poured into G0 cc. of watercontaining 1 gram of potassium iodide. The crystals were separated andpurified by boiling out with isopropyl alcohol. A yield of 0.4 gram ofYa product having a melting point of 2'l0-2'l1"V C. was obtained. Amethanol solution of the compound has an absorption maximum at 540 ma. Y

Example VI A mixture of 2.85 grams of glutaconaldehyde dianilhydrochloride, 4.3 grams of the compound of Example III, 1 cc. ofpiperidine and. 50 cc. of methanol was heated at reflux for 30 minutes.The reaction mixture was poured into 300 cc. of water containing 5 gramsof potassium iodide. The precipitated product was filtered and boiledout with isopropyl alcohol. A yield of 3.7 grams of a compound having amelting point of 195- 198 C. was obtained. A methanol solution of theproduct has an absorption at 624 ma.

The anions of the foregoing thiazolone cyanine dyesalts may be replacedby other anions, such as iodide, thiooyanate or perchlorate ions bytreating an alcohol solution of the halogen salt l5 with an aqueous oraqueous-alcohol solution containing a sodium or potassium salt of thedesired anion.

The following examples describe in detail the Y improved and simpliedmethod of preparing trinuclear cyanine dyes from the foregoingthiazolone cyanine dye intermediates, but it is to be understood thatthey are given merely for the purpose of illustration and are not to beconstrued as limitative.

Example VII A mixture of 0.35 gram of 3-al1ylrhodanine, 0.8 gram of theintermediate of Example I, 50 cc. of methanol, and 0.5 ec. oftrethylamine was heated at reflux for 5 minutes. The crude dye wasboiled out with methanol and finally crystallized from pyridine. A yieldof 1.25 grams of a product melting above 295 C. was obtained. Theabsorption maximum of this dye in a methanol solution is 610 ma.

Example VIII A mixture of 0.35 gram of 3-all`ylrhcdanne, 1.03 grams ofthe intermediate f Example III, 50 cc. of methanol and I cc. oftriethylamine was heated at reiiux for l minutes. After cooling, the dyewas separated and puriiied by boiling out with methanol. A yield of 0.5gram of a product melting at TTS-175 C. was obtained. The absorptionmaximum in methanol is 594 me. When the dye is incorporated into aphotographic emulsion the sensitization maximum is 650 mp.

Example IX A mixture of 0.6 gram of the intermediate of Example V, 0.2gram of 3-methyl-l-phenylpyrazolone, 20 cc. of methanol, and 1 cc. oftriethylamine was heated at reflux for minutes. Ihe very slightlysoluble dye was filtered oi and purified by boiling out with methanol. Ayield of 0.6 gram of the purified dye was obtained.

A mixture of 1.2 grams of the intermediate of Example VI, 0.5 gram of3-allyl-1-1nethyl2thio hydantoin, 25 cc. of methanol and 1 cc. oftriethylamine was heated at reflux for 5 minutes. After cooling the dyecrystals were removed and purified by boiling out with methanol. A yieldof 0.5 gram of a product melting at 199-203 C. was obtained. Theabsorption maximum in methanol is 621 mfr. The sensitization of aphotographic emulsion is extended to '720 my.

A mixture of 0.5 gram of the product of Example II, 0.2 gram ofB-allylrhodanine cc. of isopropyl alcohol, and 0.5 cc. of triethylaminewas heated at reflux for 10 minutes. The dye separated on cooling andwas purified by boiling,r out with isopropyl alcohol. A yield of 0.4gram of the dye was obtained. The absorption maximum of a methanolsolution is 583 mp. When incorporated in a photographic emulsion themaximum sensitization is at 640 me.

The diagrammatic spectrograms constituting the accompanying drawingillustrate the regions of the spectrum to which some of the trinuclearcyanine dyes will sensitize a gelatine silverhalide emulsion containingabout Ll--5% of silverhalide and the extent of the sensitization atvarious wavelengths; Figures 1 to 3 of this drawing illustrate thesensitizing properties of the dyes prepared in accordance with ExamplesVIII, X, and XI, respectively.

This application is a continuation-in-part of my copending applicationSerial No. 66,574, filed December 21, 1948; now Patent No. 2,516,730.

While the present invention has been described in considerable detailwith reference to certain preferred procedures and materials employed,it is understood that the improved process of preparing trinucleareyanine-dyes is not limited thereto, and that numerous variations andmodifications described in the foregoing specification may be made as,for example, the dyes which contain a thioketone group in the terminal-nembered heterocyclic nitrogenous nucleus, as illustrated in ExamplesVII, VIII, and XI, may be further treated with a quaternizing compoundsuch as methyl iodide. The quaternized compound is then condensed underreilux conditions with a cyclammonium base or salt of the type used incyanine dyes, such as 2-methylbenzothiazole ethiodide and the like,having a reactive methyl group in a-position to the nitrogen atomthereof, in the presence of a basic condensing agent such as pyridine.In the first reaction (alkylation), the trinuolear dye is modied to theextent that the nitrogen atom in the 3-position of the oxazoledione,hydantoin or rhodanine ring is quaternized and the sulfur atom in the2-position is converted to a thioether group. In the second reaction(condensation), the alkylated trinuclear cyanine dye is condensed with acyclammonium base or salt whereby symmetrical tetranuclear and newunsymmetrical tetranuclear cyanine dyes are obtained. Accordingly, thescope of` my invention is to be limited solely by the appended claims.

I claim:

1. A photographic gelatino silver-halide emulsion containing atrinuclear cyanine dyestuii of the following general formula:

wherein In represents an integer of from 1 to 3, R represents a memberselected from the class consisting of hydrogen and lower alkyl groups, Rbeing lower alkyl only when m represents 1, R1 and Re represent a memberselected from the class consisting of lower alkyl, allyl, aryl andaralkyl groups of the benzene and naphthalene series, R3 represents amember selected from the class consisting or" lower alkyl, lowerhydroxyalkyl, lower alkoxyalkyl, aryl and aralkyl groups of the benzeneand naphthalene series, X represents an acid radical, Y represents theresidue of a 5mernbered heterocyclic nitrogenous ring 11 12 system, andZ represents the atoms necessary to 4. A photographic gelatinesilver-halide emulcomplete a heterooyclic ntrogenous system. sioncontaining a trnuclear cyanne dyestul of 2. A photographic gelatnosilver-halide emulthe following structure: sion containing a trinuclearcyanne dyestuff of S the following structure: CH3--CH=CH-CH=?`S s* CH sS Il /C-OH H C =C n l N N S=C\ /o-OB 0=C\ C=CHC om l l? xl/ \N lo 02H5CH10H=CH2 l CH3 CzHl I THOMAS R. THOMPSON. Br 3. A photographic gelatnosi1ver-ha1ide emul- 15 No references cited.

sion containing a trnuclear cyanine dyestuf of the following structure:

1. A PHOTOGRAPHIC GELATINO SILVER HALID EMULSION CONTAINING A TRINUCLEARCYANINE DYESTUFF OF THE FOLLOWING GENERAL FORMULA: